The Illusion of Sex
In the Illusion of Sex (Fig. V.88-1), two faces appear side by side. One appears female, and the other appears male. In fact, both images are of the same fact that has been manipulated only very slightly (this illusion was originally published in Russell, 2009). The original face is not of an actual person; it is an androgynous face that was produced by morphing together average male and average female faces. These average faces were created by morphing together 22 male faces and 22 female faces. This androgynous face shown in Figure V.88-2. (excerpt)
Russell, Russell. "The Illusion of Sex." In The Oxford Compendium of Visual Illusions, edited by Arthur Shapiro and Dan Todorovic, 620-623. Oxford: Oxford University Press, 2017.